Thank you for reaching out and offering your kinds words.  They are VERY much appreciated and help me feel less alone.  I feeling like I am drowning in a sea of confusing emotions.  

Hi Jersey,

I'm really sorry you're going through this. I don't personally understand the bisexual experience either, since I'm not bisexual, but there is a stereotype that bisexual people can't commit, can't be happy with one person, and often can't be happy no matter who they're with in a given moment because they simultaneously desire what they aren't experiencing right then. That said, there are plenty of bisexual people who don't fit that stereotype at all and call that an awful lie. I think the stereotype comes from people who cheat and happen to be bisexual. It's not an identity issue.

If you want a monogamous relationship, both partners have to be willing to commit fully to the other, regardless of sexuality. Both people are giving up opportunities (if that's how you view it) to be with other people. Gender doesn't matter. Being attracted to both genders doesn't matter. Understand what he's saying- committing to you is denying what he wants and who he is. That means he wants to be with more than only you and he associates that desire with his identity. That's a pretty intense statement, to say he has to sleep with multiple people in order to be who he is. I don't know how the poly thing works and I have heard it described as an orientation, but idk. Maybe if you're looking for clarity, repeat those things back to him and make sure that's what he means. I think the conclusions you've drawn from the multiple affairs are likely correct.

Irish Girl, I am so sorry you are going through this.  There is so much to process, and it can be incredibly confusing and painful.  I encourage you to take your time.  From what I have read, having an open relationship is a lot of work.  Communication, honesty, and respect are all needed for it to be a success.  It sounds like your gut is warning you against entering into one at this time.  Listen to that. 

This is just my opinion, but what if you looked at this differently?  He is framing this as an identity issue, which taps into your compassion and love.  What if you reframe this as a respect issue? Do you feel loved and respected?  Is his treatment of you something you would encourage your children to accept from a partner?  Your needs and wants are important.  You are allowed to have deal breakers.  You asked him to leave because of the cheating and lies - not because of his orientation.

Do you have a trusted friend, relative, or counselor you could talk to?  You need support.  You matter.
And keep reading and posting here, as Elle suggested.  We understand what you are going through.
 

My wife came out to me as lesbian about two months ago.  Her awareness of her transition from what she thought had been lifelong heterosexuality had been ongoing for a little over a year.  Prior to coming out to me, she had maintained, both to me and to our couples therapist, that her difficulties within our marriage stemmed entirely from my inconsiderate behavior.  And I really had been inconsiderate and probably emotionally abusive: I was so angry and hurt by what I thought was her lack of interest in our marriage that I moved into a back bedroom and barely spoke to her for several weeks; I stopped telling her I loved her because I wasn't sure I did.  Greatly complicating these already difficult issues, my wife had no interest in sexual intimacy with me during the entire period dating back nearly two years prior to her coming out.  I accept and support my wife's transition and of course that transition explains at least in part the domestic difficulties we experienced.  My problem now is that I can't stop blaming myself for pushing her out the door seeking the love and affection I denied her.  I am obsessed with my past misbehavior because I cannot rule out that it had a great deal to do with her transition and because it (my misbehavior) deprived us both of months of domestic enjoyment that would have created such a more sharing environment for her transition.  I am so obsessed with my misbehavior that I have entered a deep depression that I think keeps me from actively understanding and supporting her transition.  I would like to enter an inpatient facility for maybe one to three weeks to address my depression.  Would anybody have an inpatient facility in the United States or Colombia (where we live) or Holland (our "permanent" residence) that you could recommend to me?